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Yard and Garden: Apple Tree Grafting

AMES, Iowa — Grafting is the best way to propogate apple trees. Horticulturists with Iowa State University Extension and Outreach guide gardeners through apple tree grafting by responding to questions and offering workshops.

I have an old apple tree that is starting to decline. How can I propagate it?

Apple trees don’t come true from seed. Grafting is the best way to propagate an apple tree. Grafted apple trees produce fruit that are identical to their parent.

Grafting is the joining together of two plant parts (scion and stock) in such a way that they unite and become one plant. When grafting fruit trees, the scion is a portion of a twig taken from the desired tree or variety. It comprises the upper portion of the graft and develops into the fruit producing branches of the new tree. The stock (rootstock) is the lower portion of the graft. The stock becomes the root system of the grafted plant.

Whip and tongue grafting is a relatively easy way to propagate an apple tree. This type of graft is made when the stock and scion are dormant. The stock and scion should be the same diameter, preferably between one-fourth and one-half inch. Scion material should be collected when fully dormant (February or early March) from the previous year’s growth. If possible, collect the scion wood when the temperature is above freezing. Place the scion wood in a plastic bag containing moist sphagnum moss or sawdust. Store the scions in the refrigerator until it’s time for grafting. Rootstock material can be obtained from a small number of mail-order nurseries. Both standard and dwarfing rootstocks are available.

The first step in whip and tongue grafting is to make a smooth diagonal cut through the stock 1 to 2 inches long. Use a sharp knife to ensure a smooth, even cut. Starting about one-third of the way down from the pointed end, make a second downward cut into the stock to form a tongue. The second cut should be .5 to 1 inch long, slanted toward the base of the first cut. Using the middle portion of the scion wood, prepare the scion in the same manner as the stock. The stock and scion are then slipped together, the tongues interlocking. Next, wrap the stock and scion firmly together with grafting tape or half-inch wide masking tape. Cut the scion off about 3 to 4 inches above the graft. There should be two or three buds on the remaining portion of the scion wood. Finally, cover the graft union area and cut end (top) of the scion with grafting wax or similar material.

If whip and tongue grafting is done in early March when the ground is still frozen, place the grafted trees in a plastic bag containing moist sphagnum moss and leave them at room temperature for seven to 10 days. Then place them in the refrigerator until the trees can be planted outdoors. Trees grafted after the soil has become workable can be planted outdoors immediately. Home gardeners may want to grow the small grafted trees in the garden for one or two years before transplanting them to their permanent site.

Will Iowa State University staff be offering any fruit tree grafting workshops this spring?

Grafting can be a bit intimidating for some gardeners. For those individuals, two grafting workshops will be offered in Iowa this spring.

March 29 in Iowa City
The first grafting workshop will be March 29 in Iowa City in conjunction with the Iowa Woodland Owners Association Spring Field Day. Rootstocks, apple scion wood, grafting tape, grafting sealant and knives will be provided. Participants also may bring their own scion wood. There is a $15 per person fee to attend the field day, plus an additional $35 per person ($60 per couple) to attend the grafting workshop. Additional information on the field day and grafting workshop can be found at http://www.iowawoodlandowners.org/docs/springfieldday2014.doc.

April 3 in Perry
The second grafting workshop will be April 3 from 6:30−8:30 p.m. at the Forest Park Museum in Perry. There is a $35 fee per person ($60 per couple) to attend the grafting workshop. As with the Iowa City workshop, rootstocks, apple scion wood and other grafting supplies will be provided. To register for the workshop, contact Pete Malmberg at 515-465-3577 or pete.malmberg@co.dallas.ia.us.

Patrick O’Malley, commercial horticulture specialist with Iowa State University Extension and Outreach, will be the presenter-instructor for both grafting workshops. For more workshop information, contact O’Malley at omall@iastate.edu or 319-337-2145.

Many local and regional horticulture events are offered by ISU Extension and Outreach. Find a listing of events at http://www.extension.iastate.edu/calendar/. Select the Horticulture (lawn, garden, tree, turf) category to view offerings by month or location.